Peaks in air pollution would increase the risk of miscarriage. It is therefore recommended to avoid efforts in case of heavy pollution.
Exposure to high levels of certain air pollutants in pregnant women leads to a high risk of miscarriage, similar to that of smoking. This is the result of a study led by Dr. Matthew Fuller of the University of Utah (US) and published on the newspaper Fertility and Sterility.
While past research assessed the risks of long-term exposure to air pollution, this study is the first to assess the short-term effects of exposure to fine particles. It reveals that a high level of nitrogen dioxide (NO2) in the air increases the risk of spontaneous miscarriage by 16%. Namely, it is an increase equivalent to that related to "smoking during the first trimester of pregnancy," says Dr. Matthew Fuller.
Pollution causes inflammation of the uterus
This study was conducted in Salt Lake City, USA, where nitrogen dioxide levels are similar to those of highly polluted cities such as London or Paris. Dr. Fuller's team analyzed the records of more than 1,300 women who had a spontaneous miscarriage and went to the city's emergency departments between 2007 and 2015. After taking into account others, Risk factors such as maternal age, they compared the rates of miscarriage with the concentrations of three common air pollutants: small particles (PM 2.5), nitrogen dioxide (NO2), and 'ozone.
The most obvious commonality between the various miscarriages is the level of nitrogen dioxide (averaging 34 micrograms per cubic meter) recorded during the seven days prior to termination of pregnancy. For now, researchers do not know how air pollution affects the fetus, but they think it can cause inflammation and oxidative stress in the uterus.
Other research to complete
Matthew Fuller concedes that the risk of miscarriage varies considerably depending on the number of weeks of pregnancy, but the study failed to take into account this data: "If we had been able to know the period of pregnancy during that the miscarriage took place, it would have been a real benefit, to know when women are most at risk, "says the researcher. While waiting for further research to complete this study, the doctor advises pregnant women to avoid efforts during polluted days and to get an indoor air filter, to reduce the risk.